1. Field of the Invention
The present invention relates to a substrate processing apparatus for and a substrate processing method of drying a surface of a substrate which is wet with a liquid. Substrates to be dried include semiconductor wafers, glass substrates for photomask, glass substrates for liquid crystal display, glass substrates for plasma display, substrates for optical disks, etc.
2. Description of the Related Art
Numerous drying methods have already been proposed in an attempt to remove a rinsing liquid adhering as a liquid film to the top surface of a substrate after cleaning with a processing liquid and rinsing with the rinsing liquid such as deionized water. One well known method among these is a drying method utilizing the Marangoni effect. This drying method is a method which dries a substrate by means of convective flows (Marangoni convection) caused from a surface tension difference. Particularly for a substrate processing apparatus of the single wafer processing, the so-called Rotagoni drying is known, which is a combination of drying utilizing the Marangoni effect and the spin drying.
In the Rotagoni drying, IPA (isopropyl alcohol) vapor and deionized water are discharged respectively from associated nozzles upon a rotating substrate from above the center of the substrate. Drying starts in an area provided with the EPA vapor, and as these nozzles gradually move toward outside in the radial direction of the substrate, the dried region spreads from the center of the substrate toward the rim thereof, and then the entire substrate is dried. In short, drying is attained as the deionized water on the substrate is removed off from the substrate due to the function of centrifugal force attributed to the rotation of the substrate and the Marangoni effect caused by discharging of the IPA vapor.
As other substrate drying method utilizing the Marangoni effect, the drying method described in JP-A-10-321587 is known. A substrate processing apparatus which performs this drying method is an apparatus which dries a substrate while plural rollers transport a cleaned and rinsed substrate. In this apparatus, a partition plate and a drainage block are arranged in series along a substrate transportation path. Hence, when a substrate on which water droplets adhere is conveyed to the partition plate, the partition plate removes most of the water droplets. While the substrate is conveyed further to the drainage block after this, due to a narrow clearance between thus transported substrate and the drainage block, water droplets which have slipped through the partition plate get diffused in the width direction of the drainage block owing to the capillary phenomenon. In addition, on the exit side of the drainage block, an inert gas containing an IPA gas is supplied toward the surface of the substrate. The supply of the gas gives rise to the Marangoni effect, whereby remaining water droplets evaporate and dry.